For marine outboard engines used to propel watercraft on fresh and/or salt water, corrosion prevention has to be taken into consideration when designing the metallic parts used in their assembly.
Typically, many, if not all, the exposed surfaces of metallic parts are provided with a corrosion resistant surface treatment. This can involve both changing the physical nature of the metal's surface and/or coating it with another corrosion resistant substance. Examples of corrosion resistant surface treatments include galvanization, non-conductive paint and conversion coating such as anodization and chromate conversion coating.
Another form of corrosion prevention consists in using sacrificial anodes, typically made of zinc, magnesium or aluminum alloys. These have a more negative electrochemical potential than the aluminum or steel from which outboard engine parts are typically made. As a result, a sacrificial anode prevents oxidation on the surface of the more cathodic metal part when it is conductively connected to it. Anodes are bolted to the outboard engine in various key locations such that there is metal-to-metal contact or a conductive connection between an anode and the part it is intended to prevent from corroding. However, there are many corrodible components and it is inconvenient to attach an anode to each. As a solution, metal cables, sometimes referred to as bonding straps, ground cables or ground leads, are used to conductively connect the anodes to components with which they do not have metal-to-metal contact and to conductively connect components to other components which have metal-to-metal contact or conductive connections with anodes.
However, these metal cables can be inadvertently snagged, during maintenance for example, thereby disconnecting the metal cables and compromising the corrosion protection of the associated part. Also, the fasteners used to fasten the cables can themselves corrode. The hardware used to install the metal cables (bolts, washers, etc.) can also damage the corrosion resistant surface treatment, thereby exposing a metallic surface to potential corrosion. Similarly, during the installation of the metal cables one can inadvertently damage the corrosion resistant surface treatment with the tools used to make the installation. Also, the metal cables running from one part to the other can be considered unsightly by some.